4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Solganik Alexander <sashas@xxxxxxxxxxxxxxxxx>
commit e4fcf07cca6a3b6c4be00df16f08be894325eaa3 upstream.
When removing a namespace we delete it from the subsystem namespaces
list with list_del_init which allows us to know if it is enabled or
not.
The problem is that list_del_init initialize the list next and does
not respect the RCU list-traversal we do on the IO path for locating
a namespace. Instead we need to use list_del_rcu which is allowed to
run concurrently with the _rcu list-traversal primitives (keeps list
next intact) and guarantees concurrent nvmet_find_naespace forward
progress.
By changing that, we cannot rely on ns->dev_link for knowing if the
namspace is enabled, so add enabled indicator entry to nvmet_ns for
that.
Signed-off-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
Signed-off-by: Solganik Alexander <sashas@xxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/nvme/target/configfs.c | 6 +++---
drivers/nvme/target/core.c | 14 ++++++++------
drivers/nvme/target/nvmet.h | 6 +-----
3 files changed, 12 insertions(+), 14 deletions(-)
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -271,7 +271,7 @@ static ssize_t nvmet_ns_device_path_stor
mutex_lock(&subsys->lock);
ret = -EBUSY;
- if (nvmet_ns_enabled(ns))
+ if (ns->enabled)
goto out_unlock;
kfree(ns->device_path);
@@ -307,7 +307,7 @@ static ssize_t nvmet_ns_device_nguid_sto
int ret = 0;
mutex_lock(&subsys->lock);
- if (nvmet_ns_enabled(ns)) {
+ if (ns->enabled) {
ret = -EBUSY;
goto out_unlock;
}
@@ -339,7 +339,7 @@ CONFIGFS_ATTR(nvmet_ns_, device_nguid);
static ssize_t nvmet_ns_enable_show(struct config_item *item, char *page)
{
- return sprintf(page, "%d\n", nvmet_ns_enabled(to_nvmet_ns(item)));
+ return sprintf(page, "%d\n", to_nvmet_ns(item)->enabled);
}
static ssize_t nvmet_ns_enable_store(struct config_item *item,
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -264,7 +264,7 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
int ret = 0;
mutex_lock(&subsys->lock);
- if (!list_empty(&ns->dev_link))
+ if (ns->enabled)
goto out_unlock;
ns->bdev = blkdev_get_by_path(ns->device_path, FMODE_READ | FMODE_WRITE,
@@ -309,6 +309,7 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)
nvmet_add_async_event(ctrl, NVME_AER_TYPE_NOTICE, 0, 0);
+ ns->enabled = true;
ret = 0;
out_unlock:
mutex_unlock(&subsys->lock);
@@ -325,11 +326,11 @@ void nvmet_ns_disable(struct nvmet_ns *n
struct nvmet_ctrl *ctrl;
mutex_lock(&subsys->lock);
- if (list_empty(&ns->dev_link)) {
- mutex_unlock(&subsys->lock);
- return;
- }
- list_del_init(&ns->dev_link);
+ if (!ns->enabled)
+ goto out_unlock;
+
+ ns->enabled = false;
+ list_del_rcu(&ns->dev_link);
mutex_unlock(&subsys->lock);
/*
@@ -351,6 +352,7 @@ void nvmet_ns_disable(struct nvmet_ns *n
if (ns->bdev)
blkdev_put(ns->bdev, FMODE_WRITE|FMODE_READ);
+out_unlock:
mutex_unlock(&subsys->lock);
}
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -47,6 +47,7 @@ struct nvmet_ns {
loff_t size;
u8 nguid[16];
+ bool enabled;
struct nvmet_subsys *subsys;
const char *device_path;
@@ -61,11 +62,6 @@ static inline struct nvmet_ns *to_nvmet_
return container_of(to_config_group(item), struct nvmet_ns, group);
}
-static inline bool nvmet_ns_enabled(struct nvmet_ns *ns)
-{
- return !list_empty_careful(&ns->dev_link);
-}
-
struct nvmet_cq {
u16 qid;
u16 size;
--
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